In recent years, mobile terminal devices equipped with touch panels, such as smartphones (multifunctional mobile phones) and tablet type mobile terminal devices, have prevailed. In such a mobile terminal device (hereinafter, referred to as a touch panel terminal) equipped with a touch panel, in general, by touching an icon, a button, or the like displayed on the display screen thereof with a finger, a user performs an operation.
Since, for example, the tablet type mobile terminal device is a mobile terminal based on a premise of being carried, the display screen size thereof is, for example, about 10 inches, and a plurality of operation icons or operation buttons are lined up in the display screen of this size. These techniques have been disclosed in, for example, Japanese Laid-open Patent Publication No. 2010-266997.